White-Tailed Deer Ecology & Management I

Contributed Oral Presentations

Contributed paper sessions will be available on-demand for the duration of the conference, then again at the conclusion of the conference.


Natal Habitat Preference during Extra-Home Range Movements in White-Tailed Deer
Nathan D. Hooven; Matthew T. Springer; Clayton K. Nielsen; Eric M. Schauber
Dispersals in white-tailed deer (Odocoileus virginianus) are driven by resource and mate competition and inbreeding avoidance, but the causes of excursions are less clear. Some excursions may represent would-be dispersal events during which suitable habitat for a new home range is not found. Suitable habitat may be related to natal habitat preference induction (NHPI), a phenomenon where animals exhibit affinities for habitat similar to that which they experienced in their natal environments. Using NHPI as a guiding hypothesis, we tested whether (1) deer respond to similarity to their natal habitat along extra-home range movements, (2) dissimilarity to natal habitat is related to termination of excursion movements, and (3) seasonality and individual behavioral variation affect these responses. During January-March 2011-2014 we captured juvenile and yearling deer (n=49) in central Illinois, USA, and fit them with GPS collars to document extra-home range movements. We analyzed 47 excursions (mean relocations: 45.53 ± 11.94 [SE]) made by 32 deer, along with 9 dispersals (mean relocations: 102.56 ± 41.88). We fit step selection functions (SSFs) to excursion and dispersal relocations and included Penrose distance (a measure of dissimilarity calculated from several landscape variables) from each individual’s natal home range as a covariate. We also plotted the relationship between Penrose distance and percent of movement completed, both pooled and for each individual movement, to examine dynamics in response to dissimilarity along movement paths. Results from top-performing SSFs indicate that deer select against natal habitat dissimilarity during these movements year-round. Among seasons, spring excursions tended to exhibit the strongest uptick in dissimilarity nearing termination, and several individual movements during spring and fall exhibited similar patterns. Our results suggest that some excursions likely represent failed dispersals due to an innate preference for natal habitat similarity and highlight the importance of individual variation in shaping movement behavior.
Impact of Helicopter Net-Gun Capture on Space Use and Movement of White-Tailed Deer
Seth T. Rankins; Jacob L. Dykes; Randy W. DeYoung; Aaron M. Foley; Timothy E. Fulbright; J. Alfonso Ortega-S.; David G. Hewitt; Landon R. Schofield; Tyler A. Campbell
The helicopter net-gun technique is a safe and efficient method for capturing large mammals. However, it is unclear if capture locations fall within the individual’s home range, or if they abandon their normal range to evade capture. Furthermore, captured animals are often transported to a central processing site and post-capture behavior is rarely evaluated. During 2019-2020, we captured 54 white-tailed deer (Odocoileus virginianus) on South Texas rangelands and transported them to a central processing site, where each was fitted with a GPS collar. We recorded GPS coordinates of capture locations and processing sites. Then we compared deer movements within and outside of their home range for 2 weeks post-capture. We used the second week post-capture data to ensure home ranges accurately reflected the individual’s movement patterns during the season they were captured. Deer returned to their 95% home range within x̄ = 25.8 hours (range: 0.5-139.5 hrs) after being transported x̄ = 2.5 km (range: 0.8-4.8 km) from the capture site. Females returned slower ( = 28.2 hrs) than males ( = 23.5 hrs), although females traveled shorter distances, 7 km and 10 km, respectively. Returning deer exhibited step lengths ( [95% CI]) of 158 m (121-198 m), 145 m (61-237 m), and 582 m (227-1,034 m) greater than mean step length within their home range during day, dusk, and night, respectively. We found 52% of capture locations fell within the individual’s 95% home range. Capture locations outside the 95% home range had a median distance of 289 m (range: 1-2,494 m) from the isopleth boundary. Our results indicate the helicopter net-gun capture method did not cause deer to flee the immediate vicinity of their home range, deer maintained high site fidelity after being transported ≤4.8 km, and all deer returned within 6 days post capture.
White-Tailed Deer Fawn Survival and Factors Affecting Recruitment on Marine Corps Base Quantico
Gisèle R. Aubin; Christa C. Nye; John H. Rohm; William M. Ford; Michael J. Cherry
Some areas in eastern North America have been restricting harvest of white-tailed deer (Odocoileus virginianus) because of perceived reductions in recruitment and population size over the last decade. Although the restoration of black bears (Ursus americanus) and the colonization of coyotes (Canis latrans) have likely increased fawn predation in some areas, limited information exists on how temporally dynamic resources and weather influence fawn survival. Therefore, we evaluated fawn survival, causes of mortality, and factors influencing mortality risk on Marine Corps Base Quantico in Northern Virginia, USA from 2008-2019. We predicted that fawn survival would (1) increase with an increase in oak mast abundance the fall before birth and decrease with an increase in winter severity during gestation; (2) increase with greater precipitation during the growing season; and (3) increase with greater land cover patch diversity, complexity, total edge and vary across land cover types. We fit 248 fawns with very high frequency collars and found predation was the leading cause of mortality (n=42; 45%). We estimated fawn survival to 133 days old during four, 3-year intervals and found survival was greater during the first interval (2008-2010; 0.71 [0.52-0.96]; survival probability [CI95%]) than the later intervals (2014-2016; 0.48 [0.35-0.66] and 2017-2019; 0.50 [0.39-0.63]). We found that for every unit increase (SD) in annual red oak (Quercus spp.) mast abundance, the hazard is reduced by 27% (β= -0.32, p= 0.01). Whereas other research has reported the effect of female maternal nutritional condition, due to the longevity of our study we were able to link fawn survival to a specific maternal resource (red oak mast) only available during gestation. Our results highlight the importance of oak mast in eastern deciduous forests, and more broadly, overwinter maternal condition on white-tailed deer recruitment.
Experimental Predator Exclusion Decreases Temporal Sexual Segregation in White-Tailed Deer
Daniel A. Crawford; Gail Morris; Mike Conner; Michael J. Cherry
Prey species often mitigate predation risk through alteration of spatiotemporal activity patterns whereby individual prey utilize temporal refugia to access high quality resources during predator downtimes. Spatiotemporal avoidance of predation risk by prey has received substantial attention; however, experimentally controlled examinations of behavioral prey responses in large terrestrial mammals are limited. Further, the effects of behavioral shifts on intra-specific interactions and their role in sexual segregation have not been explored. To assess the effects of predation risk on intra-specific interactions in white-tailed deer (Odocoileus virginianus), we monitored deer activity with 16 passive, infra-red motion-triggered cameras during the fawning and fawn rearing seasons across four pairs of predator exclusion and control plots (~40 ha) from 2015-2018. We estimated the coefficient of activity overlap (d̂) of males, females, and nursery groups using kernel density estimation of detection time-stamps within treatments and across treatments within demographic groups. All demographic groups exhibited shifts in activity associated with predation risk treatment, and inter-demographic overlap of all group pairings was significantly greater in predator exclusion plots with male-nursery group overlap exhibiting the greatest difference between predator exclusion (d̂ = 0.91, CI: 0.87-0.95) and control plots (d̂ = 0.67, CI: 0.57-0.76). We observed intra-demographic treatment effects of risk across all groups, but the magnitude of the effect differed suggesting that, while neonatal predation risk contributes to sexual segregation in deer, the degree of spatiotemporal segregation is dependent on inter-demographic variability in responses to predation risk rather than demographic-specific susceptibility to predator-induced mortality.
Movements of Female White-Tailed Deer and Hunters in the Southern Appalachian Mountains
Jacalyn Rosenberger; Adam Edge; Cheyenne Yates; Karl Miller; David Osborn; Charlie Killmaster; Kristina Johannsen; Gino D’Angelo
Harvest success rates for male white-tailed deer (Odocoileus virginianus) per available days for harvest declined 64% from 1979 to 2018 in the Southern Appalachian Mountains of North Georgia, indicating sharp decreases in deer populations. Information on the effects of space use by hunters on deer movements is needed to evaluate the impacts of potential management decisions with regards to hunting opportunities. This study took place on two large Wildlife Management Areas (WMAs): Blue Ridge and Coopers Creek totaling 212 km2. We evaluated fine-scale movements of deer and hunters during the 2018-2019 and 2019-2020 hunting seasons. We obtained 30-min locations from 31 GPS-collared adult does and recruited 75 hunters to carry GPS units programmed to collect 30-sec locations while they hunted. We will present results of doe home range and movement rate comparisons among pre-hunt, hunt, and post-hunt time periods. We will also provide a comparison of deer movement metrics to those of hunters, such as proximity to roads and wildlife openings (food plots). Finally, we will present maps of relative hunting pressure across the WMAs. Results will help inform the following: 1) hunting pressure and distribution of hunters across the WMAs, and thus, the harvest vulnerability of adult does, and 2) if refuge areas for deer currently exist and/or if there is potential to create refuges by limiting hunter access. Ultimately, this information will aid managers in their efforts to minimize the effects of hunting on the declining deer population while continuing to provide recreational opportunities for hunters.
Prion Protein Polymorphisms in Michigan White-Tailed Deer
Caitlin Ott-Conn; Julie Blanchong
Chronic Wasting Disease (CWD), a well described transmissible spongiform encephalopathy of the cervid family is associated with aggregation of an abnormal isoform (PrPCWD) of the naturally occurring host prion protein (PrP). Polymorphisms within the prion protein gene (Prnp) have been associated with variation in CWD susceptibility, incubation, progression, and PrPCWD accumulation. We analysed nucleic acid sequences and assigned haplotypes in 577 free-ranging white-tailed deer (Odocoileus virginianus) from 9 CWD-affected counties in Michigan. Sampling included 185 CWD positive deer and 392 for which CWD was not detected (ND). We found 12 polymorphic sites of which 5 are non-synonymous and result in a change in PrP amino acid composition. Only two polymorphic sites were found exclusively in ND individuals but were very rare. Forty-nine diplotypes comprised of 13 haplotypes were found, of which 10 have previously been described. Using logistic regression, we found haplotype C was significantly more prevalent in CWD ND individuals (p < 0.01). Additionally, we found diplotype BC to be significantly associated with CWD ND status (p < 0.01). As the non-synonymous polymorphism that distinguishes haplotype C results in a change to amino acid 96 (G96S), our findings are consistent with previous studies on CWD susceptibility in white-tailed deer. Prevalence of the protective haplotype C (24.32% - 48.65%) varied among the 9 counties, highlighting differential population susceptibility. Characterizing geospatial variation of this susceptibility will help inform and target CWD management strategies in Michigan.
The Influence of White-Tailed Deer Browsing on Vegetation and Avian Communities in Fenced and Unfenced Timber Harvests
Halie A. Parker; Dan Heggenstaller; Jeffery T. Larkin; Joseph Duchamp; Michael Tyree; Jeffery L. Larkin
Forests of eastern North America have been negatively impacted by excessive white-tailed deer (Odocoileus virginianus) browsing for decades. Previous studies provided insight regarding how deer-driven changes in forest structure, tree species composition, and microhabitat negatively impact forest birds. However, such studies used relatively small plot sizes with low replication, limiting the transferability of findings to operational-scale timber harvests. We studied the influence of white-tailed deer browsing on vegetation and avian communities in paired fenced and unfenced regenerating timber harvests in Pennsylvania. Based on previous research, we predicted that some avian species would be more positively associated with vegetation conditions in fenced harvests than unfenced harvests. Proportion of browsed woody stems was higher in unfenced harvests, whereas fenced harvests had greater horizontal and vertical vegetation density. Woody stem density did not differ between fenced and unfenced harvests, but the average height for several woody species was taller in fenced harvests. Breeding bird communities did not differ between fenced and unfenced harvests, but density of some species did. As predicted, Chestnut-sided Warbler (Setophaga pensylvanica) density (indiv./ha) was greater in fenced versus unfenced harvests, while Common Yellowthroat (Geothlypis trichas) density was similar between the two treatment types. Territory settlement results revealed Chestnut-sided Warbler selected for fenced harvests, whereas the Common Yellowthroat was indifferent. Initial findings from this study suggest deer-induced impacts on vegetation in regenerating timber harvests can have considerable influence on territory selection decisions and abundances of some avian species and that the settlement surveys provide insight into habitat selection patterns not detected by breeding season surveys.
Multi-Scale Comparisons of Methods to Evaluate White-Tailed Deer Browsing Intensity in Forests of the Central Hardwood Region
Richard Sample; Michael A. Jenkins
White-tailed deer (Odocoileus virginianus) browse leaves and twigs of woody species, and when severe, sustained browsing shifts composition towards greater dominance of less palatable species. Although individual studies have addressed the palatability of selected species, few studies have quantified browse preference of species at large scales. Furthermore, while many methods to evaluate browsing intensity exist, the relative effectiveness of different methods at multiple scales is unknown. Therefore, we assessed woody browse preference across Indiana, and examined relationships among four methods of measuring browse intensity (twig-age method, oak sentinel method, assessment of herbaceous indicator species, and proportional browse). We counted available and browsed twigs along 210 fifty-meter transects across 20 different landscapes, spanning three unique regions of Indiana (60 landscapes total). Landscapes were approximately 3.2 X 3.2 km in size, and were randomly selected to represent regions. Along the same transects, we recorded twig age of seedlings and saplings, heights of jack-in-the-pulpit (Arisaema triphyllum; previously shown to be an indicator of intense browsing), and survival, browse and growth rates of planted northern red oak (Quercus rubra) seedlings. Of 49 species sampled across the state, 19 were significantly preferred or avoided for browse, and 17 were marginally preferred or avoided. However, preference for most species did not change across regions. Overall, correlations between metrics were weaker at the woodlot scale, than at the landscape scale, suggesting that browse intensity should be examined at larger scales than individual woodlots. Our results highlight two important findings. First, preferred species may face declines in forests under heavy browse pressure from deer. Second, the utility of different methods to measure browse intensity vary with different regions and landscape configurations. Together, our results help inform deer management across a range of spatial scales.
Philopatry and Intraspecific Variation in Space Use of White-Tailed Deer
W. Hunter Ellsworth; Richard B. Chandler; L. Mike Conner; Elina P. Garrison; Karl V. Miller; Michael J. Cherry
Two important metrics of an individual’s space use are home range size and philopatry. Home range size can provide understanding of an individual’s life history needs and habitat quality. Philopatry can give insight on temporal variations in life history requisites or habitat quality. We investigated how intrinsic and extrinsic (biological, landscape composition and configuration, and disturbance) factors influenced seasonal space use of white-tailed deer (Odocoileus virginianus) in the Florida Panther National Wildlife Refuge and Big Cypress National Preserve in South Florida, a region shaped by a seasonal hydrological regime and frequent fire. We classified seasons on both hydrological (wet and dry seasons, n = 152 GPS collared deer) and biological (fawning, rearing, rut, and post-rut seasons, n = 188 GPS collared deer) time scales. Seasonal home range size was primarily a function of sex, vegetation community, and landscape structure. Across all seasons, male home ranges were larger than females. Important vegetation communities and landscape structure varied by both hydrological and biological seasons. Increasing edge density and decreasing diversity decreased home ranges during hydrological seasons. Distance to pine flatwoods, cypress forests, and prairies decreased home range size across several seasons; these effects are likely mediated by water levels and seasonal forage opportunities. Disturbance covariates had little effect on home range size across all seasons, suggesting that deer are well adapted to disturbance in this system, however vegetative communities may function as proxies for disturbance regimes. Philopatry was stronger for females than males across all seasons, likely due to an unpredictable environment, incurred costs of reproduction, and increased predation risk for females. Assessing the effects of multiple biological, landscape, and disturbance factors on space use allows for a relative comparison of these factors, illuminating the importance of sex, landscape structure, and certain vegetation communities in a seasonally unpredictable environment.
Development of a Sightability Model for Helicopter Surveys Using Surrogates of White-Tailed Deer
Jordan Ryan Dyal; Karl V. Miller; Michael J. Cherry; Gino J. D’Angelo
On large management units where terrain allows observation of white-tailed deer (Odocoileus virginianus) from the air, helicopter surveys can provide managers with cost-effective and accurate estimates of population abundance. However, imperfect detection of deer biases abundance estimates resulting in potentially inappropriate management recommendations (e.g., harvest prescriptions). Sightability estimators are designed to model detection heterogeneity based on factors that affect observer detection of target animals. Sightability models have been developed for numerous ungulate species; however, detection probability of white-tailed deer during helicopter surveys in Florida has not yet been established. Our objective was to model detection probability of white-tailed deer as a function of covariates including distance from transect, vegetation obstruction, and light conditions to improve population estimates derived from helicopter surveys. We conducted our study on a 2,620-ha study area within a 120,968-ha cattle ranch in central Florida. We placed 3-D archery targets as surrogates for white-tailed deer at randomly selected locations unknown to observers across a combination of distances and vegetation types. We conducted 12 flights during July 2019 for a total of 336 potential observations of surrogates. Detection probability on the flight path ranged from 0.95 (95% CI = 0.89-0.98) to 0.05 (95% CI = 0.01-0.18). Our results indicated that distance from the transect and vegetative obstruction negatively affect detection of deer, especially when vegetative obstruction is greater than 50% and distances greater than 50 m; however, while light had no effect. Observers simultaneously recorded live deer during flights, of which only 41% of groups were observed while movement was occurring. Our results demonstrate support for using stationary 3-D archery targets as surrogates of deer during model development. We recommend adopting our methods in other landscapes and management units to develop sightability models to account for imperfect detection of white-tailed deer.


Contributed Oral Presentations
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